Abstract
Photometric redshifts are a key component of many science objectives in the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). In this paper, we describe and compare the codes used to ...compute photometric redshifts for HSC-SSP, how we calibrate them, and the typical accuracy we achieve with the HSC five-band photometry (grizy). We introduce a new point estimator based on an improved loss function and demonstrate that it works better than other commonly used estimators. We find that our photo-z’s are most accurate at 0.2 ≲ zphot ≲ 1.5, where we can straddle the 4000 Å break. We achieve σΔzphot/(1 + zphot) ∼ 0.05 and an outlier rate of about 15% for galaxies down to i = 25 within this redshift range. If we limit ourselves to a brighter sample of i < 24, we achieve σ ∼ 0.04 and ∼8% outliers. Our photo-z's should thus enable many science cases for HSC-SSP. We also characterize the accuracy of our redshift probability distribution function (PDF) and discover that some codes over-/underestimate the redshift uncertainties, which has implications for N(z) reconstruction. Our photo-z products for the entire area in Public Data Release 1 are publicly available, and both our catalog products (such as point estimates) and full PDFs can be retrieved from the data release site, 〈https://hsc-release.mtk.nao.ac.jp/〉.
Peptide-coding genes OsIMA1 and OsIMA2 are strongly induced under iron deficiency, and positively regulate a major pathway of iron uptake and translocation in rice, enhancing the iron deficiency ...response.
Abstract
Under low iron (Fe) availability, plants transcriptionally induce various genes responsible for Fe uptake and translocation to obtain adequate amounts of Fe. Although transcription factors and ubiquitin ligases involved in these Fe deficiency responses have been identified, the mechanisms coordinating these pathways have not been clarified in rice. Recently identified Fe-deficiency-inducible IRON MAN (IMA)/FE UPTAKE-INDUCING PEPTIDE (FEP) positively regulates many Fe-deficiency-inducible genes for Fe uptake in Arabidopsis. Here, we report that the expression of two IMA/FEP genes in rice, OsIMA1 and OsIMA2, is strongly induced under Fe deficiency, positively regulated by the transcription factors IDEF1, OsbHLH058, and OsbHLH059, as well as OsIMA1 and OsIMA2 themselves, and negatively regulated by HRZ ubiquitin ligases. Overexpression of OsIMA1 or OsIMA2 in rice conferred tolerance to Fe deficiency and accumulation of Fe in leaves and seeds. These OsIMA-overexpressing rice exhibited enhanced expression of all of the known Fe-deficiency-inducible genes involved in Fe uptake and translocation, except for OsYSL2, a Fe–nicotianamine transporter gene, in roots but not in leaves. Knockdown of OsIMA1 or OsIMA2 caused minor effects, including repression of some Fe uptake- and translocation-related genes in OsIMA1 knockdown roots. These results indicate that OsIMA1 and OsIMA2 play key roles in enhancing the major pathway of the Fe deficiency response in rice.
ABSTRACT
Feasibility of the Alcock Paczynski (AP) test by stacking voids in the 21 cm line intensity field is presented. We analyse the IllustrisTNG simulation to obtain the 21 cm signal map. We then ...randomly distribute particles depending on the 21 cm intensity field to find voids by using publicly available code, VIDE. As in the galaxy clustering, the shape of the stacked void in the 21 cm field is squashed along the line of sight due to the peculiar velocities in redshift space, although it becomes spherical in real space. The redshift-space distortion for the stacked void weakly depends on redshift and we show that the dependency can be well described by the linear prediction, with the amplitude of the offset being free parameters. We find that the AP test using the stacked voids in a 21 cm intensity map is feasible and the parameter estimation on Ωm and w is unbiased.
Abstract
We present and characterize the catalog of galaxy shape measurements that will be used for cosmological weak lensing measurements in the Wide layer of the first year of the Hyper Suprime-Cam ...(HSC) survey. The catalog covers an area of 136.9 deg2 split into six fields, with a mean i-band seeing of 0${^{\prime\prime}_{.}}$58 and 5σ point-source depth of i ∼ 26. Given conservative galaxy selection criteria for first-year science, the depth and excellent image quality results in unweighted and weighted source number densities of 24.6 and 21.8 arcmin−2, respectively. We define the requirements for cosmological weak lensing science with this catalog, then focus on characterizing potential systematics in the catalog using a series of internal null tests for problems with point-spread function (PSF) modeling, shear estimation, and other aspects of the image processing. We find that the PSF models narrowly meet requirements for weak lensing science with this catalog, with fractional PSF model size residuals of approximately 0.003 (requirement: 0.004) and the PSF model shape correlation function ρ1 < 3 × 10−7 (requirement: 4 × 10−7) at 0${^{\circ}_{.}}$5 scales. A variety of galaxy shape-related null tests are statistically consistent with zero, but star–galaxy shape correlations reveal additive systematics on >1° scales that are sufficiently large as to require mitigation in cosmic shear measurements. Finally, we discuss the dominant systematics and the planned algorithmic changes to reduce them in future data reductions.
The CFHT large area U-band deep survey (CLAUDS) Sawicki, Marcin; Arnouts, Stephane; Huang, Jiasheng ...
Monthly notices of the Royal Astronomical Society,
11/2019, Letnik:
489, Številka:
4
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
The Canada–France–Hawaii Telescope (CFHT) Large Area U-band Deep Survey (CLAUDS) uses data taken with the MegaCam mosaic imager on CFHT to produce images of 18.60 deg$^2$ with median seeing ...of FWHM = 0.92 arcsec and to a median depth of $U = 27.1$ AB (5$\sigma$ in 2 arcsec apertures), with selected areas that total 1.36 deg$^2$ reaching a median depth of $U=27.7$ AB. These are the deepest U-band images assembled to date over this large an area. These data are located in four fields also imaged to comparably faint levels in $grizy$ and several narrowband filters as part of the Hyper Suprime–Cam (HSC) Subaru Strategic Program (HSC-SSP). These CFHT and Subaru data sets will remain unmatched in their combination of area and depth until the advent of the Large Synoptic Survey Telescope. This paper provides an overview of the scientific motivation for CLAUDS and gives details of the observing strategy, observations, data reduction, and data merging with the HSC-SSP. Three early applications of these deep data are used to illustrate the potential of the data set: deep U-band galaxy number counts, z$\sim$ 3 Lyman break galaxy selection, and photometric redshifts improved by adding CLAUDS U to the Subaru HSC $grizy$ photometry.
Abstract
We present an optically-selected cluster catalog from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The HSC images are sufficiently deep to detect cluster member galaxies down to ...M* ∼ 1010.2 M⊙ even at z ∼ 1, allowing a reliable cluster detection at such high redshifts. We apply the CAMIRA algorithm to the HSC Wide S16A dataset covering ∼232 deg2 to construct a catalog of 1921 clusters at redshift 0.1 < z < 1.1 and richness ${\skew7\hat{N}}_{\rm mem}>15$ that roughly corresponds to M200m ≳ 1014 h−1 M⊙. We confirm good cluster photometric redshift performance, with the bias and the scatter in Δz/(1 + z) being better than 0.005 and 0.01, respectively, over most of the redshift range. We compare our cluster catalog with large X-ray cluster catalogs from the XXL and XMM-LSS (the XMM Large Scale Structure) surveys and find good correlation between richness and X-ray properties.We also study the mis-centering effect from the distribution of offsets between optical and X-ray cluster centers. We confirm the high (>0.9) completeness and purity for high-mass clusters by analyzing mock galaxy catalogs.
ABSTRACT
We investigate the robustness of baryon acoustic oscillations (BAO) measurements with a photometric galaxy sample using mock galaxy catalogues with various sizes of photometric redshift ...(photo-z) uncertainties. We first conduct the robustness of BAO measurements, assuming we have a perfect knowledge of photo-z uncertainties. We find that the BAO shift parameter α can be constrained in an unbiased manner even for 3 per cent photometric redshift uncertainties up to z ∼ 1. For instance, α = 1.006 ± 0.078 with 95 per cent confidence level is obtained from 3 per cent photo-z uncertainty data at z = 1.03 using the sample of M* ≥ 1010.25 M⊙ h−2. We also find that a sparse galaxy sample, e.g. <2 × 10−4 h Mpc−13, causes additional noise in the covariance matrix calculation and can bias the constraint on α. Following this, we look into the scenario where incorrect photometric redshift uncertainties are assumed in the fitting model. We find that underestimating the photo-z uncertainty leads to a degradation in the constraining power on α. However, the constrained value of α is not biased. We also quantify the constraining power on Ωm0 assuming the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST)-like covariance and find that the 95 per cent confidence level is σ(Ωm0) ∼ 0.03–0.05 corresponding to the photo-z uncertainties of 1–3 per cent, respectively. Finally, we examine whether the skewness in the photometric redshift can bias the constraint on α and confirm that the constraint on α is unbiased, even assuming a Gaussian photo-z uncertainty in our model.
Abstract
We present measurements of cosmic shear two-point correlation functions (TPCFs) from Hyper Suprime-Cam Subaru Strategic Program (HSC) first-year data, and derive cosmological constraints ...based on a blind analysis. The HSC first-year shape catalog is divided into four tomographic redshift bins ranging from $z=0.3$ to 1.5 with equal widths of $\Delta z =0.3$. The unweighted galaxy number densities in each tomographic bin are 5.9, 5.9, 4.3, and $2.4\:$arcmin$^{-2}$ from the lowest to highest redshifts, respectively. We adopt the standard TPCF estimators, $\xi _\pm$, for our cosmological analysis, given that we find no evidence of significant B-mode shear. The TPCFs are detected at high significance for all 10 combinations of auto- and cross-tomographic bins over a wide angular range, yielding a total signal-to-noise ratio of 19 in the angular ranges adopted in the cosmological analysis, $7^{\prime }<\theta <56^{\prime }$ for $\xi _+$ and $28^{\prime }<\theta <178^{\prime }$ for $\xi _-$. We perform the standard Bayesian likelihood analysis for cosmological inference from the measured cosmic shear TPCFs, including contributions from intrinsic alignment of galaxies as well as systematic effects from PSF model errors, shear calibration uncertainty, and source redshift distribution errors. We adopt a covariance matrix derived from realistic mock catalogs constructed from full-sky gravitational lensing simulations that fully account for survey geometry and measurement noise. For a flat $\Lambda$ cold dark matter model, we find $S\,_8 \equiv \sigma _8\sqrt{\Omega _{\rm m}/0.3}=0.804_{-0.029}^{+0.032}$, and $\Omega _{\rm m}=0.346_{-0.100}^{+0.052}$. We carefully check the robustness of the cosmological results against astrophysical modeling uncertainties and systematic uncertainties in measurements, and find that none of them has a significant impact on the cosmological constraints.
Abstract
Constraining the relation between the richness N and the halo mass M over a wide redshift range for optically selected clusters is a key ingredient for cluster-related science in optical ...surveys, including the Subaru Hyper Suprime-Cam (HSC) survey. We measure stacked weak-lensing profiles around 1747 HSC CAMIRA clusters over a redshift range of 0.1 ≤ zcl ≤ 1.0 with N ≥ 15 using the HSC first-year shear catalog covering ∼140 deg2. The exquisite depth and image quality of the HSC survey allow us to measure lensing signals around high-redshift clusters at 0.7 ≤ zcl ≤ 1.0 with a signal-to-noise ratio of 19 within the comoving radius range $0.5\lesssim R\lesssim 15\, h^{-1}\:{\rm Mpc}$. We constrain the richness–mass relations P(ln N ∣ M, z) of HSC CAMIRA clusters assuming a log-normal distribution without informative priors on model parameters, by jointly fitting to the lensing profiles and abundance measurements under both Planck and WMAP cosmological models. We show that our model gives acceptable p-values when we add redshift-dependent terms proportional to ln (1 + z) and ln (1 + z)2 in the mean and scatter relations of P(ln N ∣ M, z). Such terms presumably originate from the variation of photometric redshift errors as a function of redshift. We show that constraints on the mean relation 〈M ∣ N〉 are consistent between the Planck and WMAP models, whereas the scatter values σln M ∣ N for the Planck model are systematically larger than those for the WMAP model. We also show that the scatter values for the Planck model increase toward lower richness values, whereas those for the WMAP model are consistent with constant values as a function of richness. This result highlights the importance of the scatter in the mass–richness relation for cluster cosmology.
ABSTRACT We present an innovative approach to constraining the non-cold dark matter model using a convolutional neural network (CNN). We perform a suite of hydrodynamic simulations with varying dark ...matter particle masses and generate mock 21 cm radio intensity maps to trace the dark matter distribution at z = 3 in the postreionization epoch. Our proposed method complements the traditional power-spectrum analysis. We compare the results of the CNN classification between the mock maps with different dark matter masses with those from the two-dimensional power spectrum of the differential brightness temperature map of 21 cm radiation. We find that the CNN outperforms the power spectrum. Moreover, we investigate the impact of baryonic physics on the dark matter model constraint, including star formation, self-shielding of H i gas, and ultraviolet background model. We find that these effects may introduce some contamination in the dark matter constraint, but they are insignificant compared to the system noise of the SKA instruments.
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